It is known to use a vertical drilling rig in oil, gas and coal bed methane well drilling. Conventional vertical drilling rigs use heavy drill pipe or drill collars in order to exert downward force on the drill bit as it enters the earth's surface and begins the well bore. As the drill bit of the conventional vertical drilling rig drills deeper below the earth's surface, it is sometimes necessary to apply force in the opposite direction of the drilling direction (pull-back force) in order to prevent placing too much weight on the drill bit and causing damage to or failure of the drill bit.
It is also known to drill oil, gas and methane wells in a vertical direction initially and then deviate or turn the well bore in increments toward a horizontal direction as the drill bit reaches the target formation. The bore hole is then continued in the horizontal direction for a distance. This method exposes a greater volume of the oil, gas and methane producing formation to the well bore and produces a higher and longer producing well. In order to covert a vertical drilling rig to accomplish the combination vertical-horizontal drilling, it is necessary to retrofit the vertical drilling rig with a top drive adapted to fit into the derrick structure and provide rotational force to the drill pipe, rather than just a rotary table and Kelly bar. Conventionally, a rotary table is fixed to the drill rig floor or base such that it does not move up and down with the drill pipe. A heavy fluted round piece of drill pipe called a Kelly bar slides through the rotary table opening and connects to the drill pipe or casing. The keys that engage with the Kelly bar impart the torque to the drill pipe string and permit the Kelly bar to raise and lower through the rotary table opening. The top drive also provides thrust and pull-back forces which are needed while drilling in the horizontal direction. However, the distances of the horizontal runs produced by conventional devices and methods are limited by the capability of the top drive to apply thrust and pull-back forces to the drill pipe. The diameters of the horizontal runs are also limited by the ability to apply thrust and pull-back forces to the drill pipe.
It is also known to use a variation of the vertical-horizontal drilling method described above which is called slant drilling. In slant drilling, a vertical oil, gas, methane drilling rig is retrofitted such that the derrick is disposed at an angle, e.g., 45° to 60° from horizontal. A top drive applies the rotational, thrust and pull-back forces to the drill pipe. It is further known to use drilling rigs commonly known as super singles for subsurface drilling applications relating to oil, gas and methane. Super single drilling rigs utilize longer Range III drill pipe lengths which are 45 feet in length. Super single drilling rigs, therefore, reduce the number of tool joint connections that are required to be made during a subsurface drilling operation. Consequently, the drilling process can be completed more quickly. Super singles utilize a top drive to rotate the drill pipe, to provide the thrust needed for the drill bit to cut and to control the steering of the cutting assembly. Conventional super singles include top drive units having limited thrust capacity and limited rotary torque capacity. Thus, the horizontal distances and bore hole diameter that may be achieved using a super single are limited.
Still further, conventional drilling rigs include power units that are separate from the drilling apparatus and therefore require multiple truckloads to transport the drill rig. Conventional oil, gas and methane drilling assemblies are not anchored to the ground so as to increase performance specifications. Instead, conventional drilling rigs use their own weight to control the machine performance specifications. As a result, convention drilling machines are very heavy and require multiple truckloads to transport. Conventional oil, gas and methane drilling rigs also use heavy weighted drill collars in the drill pipe string in order to provide the thrust force to the drill pipe and a winch and cable system to provide the pull-back force. Weighted drill collars, however, are not effective in the horizontal direction. Some conventional oil, gas and methane drilling rigs use hydraulic cylinders to provide the trust and pull-back forces. Further, conventional oil, gas and methane machines frequently damage the threaded end of a drill string section when the top drive or rotary table engages the threaded end of the drill string section.
Still further, conventional drilling assemblies do not include a roller drill pipe guide bushing assembly adapted to reduce the wear and damage to the drill pipe string. Conventional drilling assemblies do not include automated drill pipe slips adapted to reduce the amount of time required to perform make-up and break-out operations on the drill pipe and/or casing tool joints. Conventional drilling assemblies do not include pipe handling arms adapted to be pinned to the sub-structure for easy removal during transport. Conventional drilling assemblies do not include a positive rack and pinion carriage (top drive) system which is adapted to provide thrust and pull-back forces to the drill pipe string and eliminate the need for cables, winches, hydraulic cylinders, chain systems and the like to provide such forces. Conventional drilling assemblies also do not include a slip spindle sub assembly which is incorporated into the top drive system and adapted to reduce damage and wear to the drill pipe or casing thread.
It would be desirable therefore, if a drilling assembly could be provided that would produce an increased capacity for drill pipe rotational, thrust and pull-back forces. It would also be desirable if a drilling assembly could be provided that would produce longer well bores and well bores having a greater diameter than those produced by conventional drilling assemblies. It would also be desirable if a drilling assembly could be provided that would be capable of entering the earth and drilling a well bore at an angle steeper than conventional horizontal directional drill assemblies. It would also be desirable if a drilling assembly could be provided that would be capable of entering the earth and drilling a well bore at an angle closer to horizontal than conventional vertical drill assemblies. It would also be desirable if a drilling assembly could be provided that would eliminate the need for heavy drill pipe or drill collars to exert downward force on the drill bit. It would also be desirable if a drilling assembly could be provided that would be more easily transported. It would also be desirable if a drilling assembly could be provided that is adapted to be anchored to the ground so as to increase performance specifications. It would also be desirable if a drilling assembly could be provided that would eliminate the need for cables, winches, hydraulic cylinders, chain systems and the like to provide rotational, thrust and pull-back forces. It would be desirable if a drilling assembly could be provided that would reduce the damage and wear to the threaded end of a drill string section when the top drive or rotary table engages the threaded end of the drill string section. It would be desirable if a drilling assembly could be provided that would reduce the amount of time required to perform make-up and break-out operations on the drill pipe and/or casing tool joints. It would be desirable if a drilling assembly could be provided that includes pipe handling arms adapted to be pinned to the sub-structure for easy removal during transport. It would be desirable if a drilling assembly could be provided that is adapted to perform vertical and horizontal drilling applications with a tube-in-tube drill string. It would also be desirable if a drilling assembly could be provided that would be adapted to continue operations in the event of a power unit failure.